I had my IUD (Mirena) inserted on June 13, 2007 after I had my son and had it removed on July 2, 2009, it took me 43 days before I got my first period, and I know some women who it's taken 90+ days to receive their first period. Your body's just trying to get back to normal, I know how frustrating it can be while your sitting in lingo, not sure weather your pregnant or when your first period will show up, but try to be patient it will happen when the time is right! It took me almost 7 months til I finally got my BFP. I am currently 21 weeks with a healthy baby boy. Good luck and hope this helps!
P.S. You should join the group how long did it take you conceive after Mirena removal, the women on there are very supportive. There's lots of women on there as well that had the copper IUD just like you.
I agree with Annie. I had the Mirena for 5 years and it took 2-3 months for my period to straighten out after removal.
It doesn't sound like you are pregnant, between the negative tests and the period. It was probably more likely just your uterus getting adjusted to having no copper IUD in it any more.